debris disk

A debris disk is a circumstellar disk of dust and debris around a fully formed star, as opposed to protoplanetary disk, which is gas around a new star (such as a protostar). Debris disks are presumed to exist consisting of debris resulting from planet and planetoid impacts. Observed disks around fully-formed stars may be interpreted as such. Impacts creating debris can occur in aged stars, but seem likely to be common toward/at the end of planet formation, and it is presumed that the solar system went through a stage of a substantial disk of such debris early in its life.

The term debris belt is also used, generally when the debris is not spread as much as in a typical disk. The term is sometimes used for a specific part of a disk that appears to be debris, e.g., within a protoplanetary disk. This is somewhat expected given planet-formation theories that presume planetoid collisions occurring at some stages. The asteroid belt is considered such a debris belt that out-lasted the solar system's planet formation.